Shares of Herbalife have been on a roller coaster since hedge fund manager Bill Ackman disclosed his short position against the nutritional supplement firm, calling it a "pyramid scheme."

Shares of Herbalife (HLF) bounce back from a sharp drop Monday morning after the New York Post reported that the company is the subject of a federal investigation. Herbalife's stock fell nearly 13% shortly after the open but finished the day up more than 1%.

The investigation was revealed after the Federal Trade Commission disclosed a list of 192 complaints against Herbalife from the past seven years in response to a Freedom of Information Law request by the newspaper.

"The FTC redacted some sections, saying it didn't have to divulge 'information obtained by the commission in a law enforcement investigation, whether through compulsory process, or voluntarily ...,'" the New York Post said in its article. "Other complaints contained a note referring to a 'pending law enforcement action.'"

The FTC said investigations are not public, and would not confirm or deny whether one exists against Herbalife.

Herbalife said that other than previously mentioned voluntary dialogue with regulators, it is "unaware of any other regulatory interest and/or investigation." Herbalife said it is demanding a correction from the New York Post. Following Herbalife's statement, shares of the company began to move off their lows, pushing into positive territory before the market's close.

Representatives from the New York Post could not be reached for immediate comment.

The newspaper said it filed its request to the FTC in December just days after activist investor Bill Ackman, who runs the $11 billion hedge fund Pershing Square, called Herbalife a pyramid scheme and publicly said that he's betting $1 billion that its stock will fall to zero.

Herbalife has been defending itself, calling Ackman's actions "yet another attempt to illegally manipulate the market by overzealous short-sellers."

A spokesperson for Third Point had no comment about the reported investigation or the list of complaints against Herbalife.

Ackman's Pershing Square could not be reached for immediate comment.

In an interview with CNNMoney last month, Ackman said he had informed the FTC of why he thinks Herbalife is a pyramid scheme that specifically preys upon low-income individuals in the United States and around the world.